Deformability of prestressed flexural reinforced concrete elements with high-tensile reinforcement steel of At1200 class

A homegrown innovation of thermo-mechanically treated high-tensile reinforced steel (AT1200 class, 30HGS2 and 30HS2 types) increases the efficiency of prestressed reinforced concrete in the construction industry. This paper analyses the deformability of prestressed flexural reinforced concrete elements with the AT1200 reinforcement steel. To study the characteristics of the stress-strain behaviour in flexural elements with the AT1200 reinforcement steel, rectangularsectioned, conventional and prestressed reinforced concrete beam elements were tested . Reference deflection of the test elements, which was used as a deformability criterion, was recorded by mechanical and strain-gauge measuring equipment. This work is part of a comprehensive study on AT1200 steel and constructional steelworks. The findings of experimental and theoretical studies are presented, addressing the effect of prestressing on the deformability in flexural reinforced concrete elements. The obtained results indicate that prestress, if applied correctly, significantly increases the stiffness (reduces the deformability) of the flexural elements. The methodology of current standards is based on a general structural theory and includes both flexural and shear strain characteristics of structures in the section over their length. The possibility of extending the method to assess deflections of the prestressed flexural elements with the studied AT1200 steel is substantiated. Empirical dependencies obtained for the л coefficient are recommended for affecting the deformability and cracking resistance of flexural elements comprising prestressed AT1200 steel and initial preoperational prestressing cracks (deflection cracks in the zone, pressed during operation).

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